The present invention relates to an apparatus for producing an image recording medium having a support member and a developer material coated thereon and, particularly, to an apparatus for applying a fine granular developer material onto a support member such as a plain paper.
In recent years, a color copier has been introduced wherein a microcapsule sheet is exposed to light through an original; the exposed microcapsule sheet is fed into a pressure-developing device together with a developer sheet (an image recording medium having a developer material applied onto a support member such as a plain paper); a latent image on the exposed microcapsule sheet is transferred to the developer sheet by the pressure-developing device; and the developer sheet is conveyed to a thermal fixing device so that a color image is formed on the developer sheet.
The developer sheet is made by applying a developer material, e.g., a material constituted with acid clay and a binder onto a support member. Apparatuses for applying the developer material to the support member are disclosed in U.S. patent application Ser. No. 07/253,614 filed on Oct. 5, 1988 and Ser. No. 07/437,516 filed on Nov. 16, 1989, assigned to the same assignee as the present invention. Each discloses an image recording medium producing apparatus of a type wherein the fine granular developer material is charged and thereby applied onto the support member.
Namely, as shown in FIG. 6, an image recording medium producing apparatus of the above-mentioned type is provided with a reservoir 50 for storing a fine granular developer material S, a feeding roller (a developer material feeding member) 52 rotating within reservoir 50 and supply roller 51 placed inside reservoir 50 and pressed against the roller 52. The feeding roller 52 and the supply roller 51 are rotated and cause the developer material S to be charged to a positive polarity by means of friction between the developer material S and rollers 51 and 52. The charged developer material S is applied to a peripheral surface of the feeding roller 52 and then is attracted to a conveying roller 53 placed opposite to the feeding roller 52.
The conveying roller 53 is supplied with negative voltage. A conveying belt 54 is extended between the conveying roller 53 and a pair of guide rollers 55. Thus, the conveying belt 54 is run by rotation of the conveying roller 53. A support member P, such as a plain paper for supporting the developer material S, is attracted to and conveyed by the conveying belt 54. Accordingly, an apparatus for conveying the support member P comprises the conveying roller 53, the conveying belt 54, and the guide rollers 55. The fine granular developer material S charged to a positive polarity is transferred and applied onto the support member P at a position where the peripheral surface of the feeding roller 52 is closest to the conveying roller 53, so that a layer m of the developer material is formed on the support member P.
Several problems exist in the image recording medium producing apparatus described above which produces uneven coating of support member P. Elements such as rollers and a belt are utilized as means for charging and feeding the fine granular developer material. The developer material is fed to a position opposite to the support member and is held on the developer material feeding member by static electricity caused by friction between the feeding member and the developer material. A layer of the developer material on the feeding member is formed with an uneven surface causing lines in a feeding direction of the feeding member because of either conglomeration of the fine granular developer material or an unevenly machined surface of the developer material feeding member, or both. Consequently, there remains in the proposed image recording medium producing apparatus a problem that the developer material cannot be applied uniformly to the support member. If the microcapsule sheet is put on the developer sheet having an uneven layer of the developer material and pressure-development is performed, an image is formed with irregular coloring.